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C3 Differentiation Help

The question goes as follows
"Find the coodinates and the nature of any stationary points on the following
y=4x-5e^x"
I know the general method, what got me was when you try to solve for x after differentiating it. When I differentiated I ended up with "4-5e^x=0" I thought I could use logs, but I don't want to become dependant on that method since C3 is a non calculator paper. Can anyone help me on this part of the question?
Original post by Fruitbasket786
The question goes as follows
"Find the coodinates and the nature of any stationary points on the following
y=4x-5e^x"
I know the general method, what got me was when you try to solve for x after differentiating it. When I differentiated I ended up with "4-5e^x=0" I thought I could use logs, but I don't want to become dependant on that method since C3 is a non calculator paper. Can anyone help me on this part of the question?

Hi. If the paper is non-calculator, then would you be expected to use logs and give your answer in terms of ln (e.g. x=ln 20) ?
Original post by George0123

Yes, that is how I expect you would have to give your answer (didn't want to give it away in my previous post)

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